Analyze the four factors one by one: (a) Substrate. The substrate is secondary.
ID: 519801 • Letter: A
Question
Analyze the four factors one by one: (a) Substrate. The substrate is secondary. If it were primary, we would predict S_N2, and if it were tertiary, we would predict S_N1. But with a secondary substrate, it could be either, so we move on to the next factor. (b) Nucleophile. NaSH indicates that the nucleophile is HS^- (remember that Na^+ is just the counter ion). HS^- is a strong nucleophile, which favors S_N2. (c) Leaving Group. Br^- is a good leaving group. This factor alone does not indicate a preference for either S_N1 or S_N2. (d) solvent. DMSO is a polar aprotic solvent, which favors S_N2.Explanation / Answer
1. The leaving group is present in a secondary carbon. This can give rise to both SN1 or SN2 product.
Nucleophile is strong and the solvent used (DMSO is a polar aprotoc solvent which favors SN2 reaction) favors SN2. So, this will be a SN2 reaction.